bokeh without blur?

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thislittlemum

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Hello All

I am quite a newbie with regards to DSLRs. I have been trying to get to grips with my second hand canon 400d + 50mm 1:1.8 lenns and have had considerable success with shooting one of my favourite subjects: food.

However, when trying to shoot my other favourite subject (my 18 month old daughter) I find that settings which achieve good bokeh with still objects just result in blur when shooting my daughter (rarely still). Is it possible with my camera and that lens to capture her in motion and achieve bokeh at the same time?

And please can someone explain why I get this blur? I like to try to understand things as I go along.

Thanks!
 
can you post an example?

sounds like you're missing focus....you have to remember that shooting at f1.8, the actual depth of field (the amount of image that is in focus) is tiny...depending on how far you are from the subject it might only be a few inches...easy to miss when you have a model that won't keep still!
 
a lens is only in true focus at a single distance.
The depth of things that are in focus becomes greater as you stop down. "smaller hole"
Bokeh is the "quality" of the out of focus areas it is not "how much is out of focus"

Blurrring be caused by three main factors......
A too long shutter speed to stop motion.
lack of focus through poor focusing.
movement of the camera through camera shake.

Any or all of those can cause your daughter to be blurred.

Depth of field "how much is in focus " is controlled by the lens aperture. (smaller hole =more. larger hole= less)

Think of "exposure " as filling a bucket with water. A full bucket + correct exposure.
This can be achieved by opening the tap further ( same as larger hole/aperture)
Or letting the tap run for longer ( same as longer shutter opening )
Either can achieve a correct exposurebut the one will alter the depth of field
whilst the other can stop motion or not.
 
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I used to get this a lot with my 450D and 50mm f1.4 and a fast toddler (my boy).
When shooting indoors, in the evening (or in any low light), I found a flash (Canon 430EX II) was a really big help. The flash has a built-in focus assist lamp that speeds up the focus no end. I set the apeture to f4 (should be were your lens is roughly the sharpest), the shutter speed to 1/40 (you don't need fast shutter speed in low light because the flash freezes the action), Auto ISO and I adjust the flash power until the Histogram looks good (type 'camera histogram' into Youtube for some tutorials - it's well worth it)
I also only use the centre focus point and use focus recompose. I found this helped a lot but it was such a long time ago that I first did this can't remember the benefits (I think it stopped the camera 'hunting')
The other mistake I made was to not take the ISO above 400 for fear of digital grain. I'd take grain over blur any day of the week, so now i'm not afraid to bump it up to 1600 to get a fast enough shutter speed.

Watch plenty of Youtube videos and practice when your kid (or kids) are in bed.
 
thanks for the advice everyone! especially fatmarley as you have first hand experience! will do exactly as you say and youtube and practice :-)
 
thislittlemum said:
However, when trying to shoot my other favourite subject (my 18 month old daughter) I find that settings which achieve good bokeh with still objects just result in blur when shooting my daughter (rarely still).

And please can someone explain why I get this blur?
Click to expand...

If you have an example photo of the blurred shots it may help us help you. Its possible the blur could be movement of toddler during exposure caused by a too slow a shutter speed or your toddler moving outside of a very small depth of field when using a large aperture (f1.8-2.8) as the exposure happens.

A still subject does not need a fast shutter speed to capture a sharp in focus photo, a moving toddler will need a shutter speed fast enough to freeze the toddlers movement. To get a faster shutter speed you may need to increase ISO until you can great a fast enough shutter speed. Flash will help if you want to freeze your toddlers movement if shooting inside in low light and do not want to increase ISO.

What settings are you using to take the still images? Without setting values or an example it's difficult to help. It's difficult to say whether settings used to capture still subjects would be ok to capture moving subjects without knowing the actual settings you used, what time of day you took the photos and whether you took the photos inside or outside (the amount of light available).

If the shutter speed is about 1/50 sec then this is probably too slow to freeze movement. I normally shoot moving wildlife and I'm usually looking for a fast shutter speed of at least 1/500 at an aperture of about f4 to give nice bokeh but this means ISO usually between 800-3200 (depending of daylight levels).
 
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